1. Field of the Invention
This invention relates to cosmetic compositions, and in particular to a composition containing fluid milk as one of its principal constituents.
2. Prior Art
Milk, and cosmetic compositions containing milk, have long been recognized as having a beneficial effect when applied to the human skin. Moreover, whole fluid milk which still contains its natural fats (butterfat) is regarded as more beneficial to the skin than skim or non-fat milk and much more beneficial than dry milk solids or liquid milk reconstituted from dry milk solids. However, fresh fluid milk contains a variety of natural enzymes and is a rich nutrient for the growth of bacteria and other organisms which contribute to the rapid souring and short shelf life of fluid milk and products containing fluid milk. As a result, untreated fresh milk can not be employed in cosmetic compositions which are normally stored at room temperature and are required to have a useful shelf life of several years or more.
The souring and spoilage of fluid milk can be inhibited and its shelf life extended by such treatment as pasteurization or sterilization (especially, pasteurization under conditions which insure the complete destruction of all enzymes and microorganisms contained in the milk) if the pasteurized or sterilized milk is stored under refrigeration and consumed within a few days, or a few weeks, of the treatment. However, it has not heretofore been possible to employ fluid milk in ordinary cosmetic compositions, even if the milk is pasteurized or sterilized, because of the necessity for storing such compositions at room temperature for long periods of time.
The spoilage of fluid milk can also be inhibited by the inclusion of large dosages of anti-enzyme (anti-oxidants), bactericidal and fungicidal agents in the milk. However, the anti-enzyme, bactericidal and fungicidal agents heretofore employed (for example, formaldehyde and sodium disulfite) are either powerful skin irritants or allergens or must be used in such large amounts that the resulting milk product is unsuitable for use in or as a cosmetic. At best, only a very small amount of fluid milk (less than 10%) treated with conventional preservatives can be incorporated in cosmetic compositions before the quantity of preservative agent required to be present reaches unacceptable levels.
As an alternative to the use of fluid milk, it has heretofore been proposed that dry milk solids, and usually non-fat dry milk solids, be employed as an ingredient in cosmetic compositions. However, as previously noted, cosmetic compositions prepared from dry milk solids are not nearly as beneficial to the skin as are cosmetic compositions prepared from whole fluid milk. Moreover, in order to prevent spoilage and to extend the shelf life of these compositions it is necessary to include preservative agents that are irritating or allergenic to the skin in these compositions. As a result, cosmetic compositions containing dry milk solids have not met with success.
In view of the recognized superiority for cosmetic purposes of whole fluid milk containing a high proportion of natural milk fats, as compared to skim milk and dry milk solids, we have carried out an intensive investigation of the problems encountered in preparing cosmetic compositions containing whole fluid milk. As a result of our investigation we have discovered that cosmetic compositions can be prepared which contain a much higher proportion of whole fluid milk and which have a shelf life under ordinary conditions of storage far in excess of comparable milk-containing cosmetics heretofore known, provided certain novel formulation criteria are observed. Specifically, we have discovered that the high milk content and the long shelf life of the cosmetic composition of the invention are attributable in large measure to the use of sterilized fluid milk containing added milk fats and to the synergistic effect of two specific preservative agents neither one of which, by itself, is capable of achieving the results obtained when the two are employed together.